Death toll from California wildfires 'large as New York City' rises to 31

Teams with dogs have begun a grim search for more dead in parts of California wine country devastated by wildfires.

Searchers resorted in some cases to using serial numbers stamped on medical implants to identify remains that turned up in the charred ruins.

New deaths confirmed today took the toll to 31, making it the deadliest week of wildfires in California history.

Many of the flames still burned out of control, and the fires grew to more than 300 square miles, an area as large as New York City.

Homes burned by a wildfire are seen Wednesday, Oct. 11, 2017, in Santa Rosa, Calif

Sonoma and Napa counties endured a fourth day of choking smoke while many residents fled to shelters or camped out on beaches to await word on their homes and loved ones.

A forecast for gusty winds and dry air threatened to fan the fires further.

Some of the state's most historic tourist sites, including Sonoma city and Calistoga in Napa Valley, were ghost towns populated only by fire crews trying to stop the advancing infernos.

Calistoga mayor Chris Canning warned that the fires were drawing closer and all of the city's 5,000 residents needed to heed an evacuation order.

Sonoma County Sheriff Robert Giordano said officials were still investigating hundreds of reports of missing people and that recovery teams would begin conducting "targeted searches" for specific residents at their last known addresses.

"We have found bodies almost completely intact, and we have found bodies that were nothing more than ash and bones," the sheriff said.

Some remains have been identified using medical devices uncovered in the scorched heaps that were once homes. Metal implants, such as artificial hips, have ID numbers that helped put names to victims, he said.

The eight new deaths confirmed on Thursday brought the total to 31. Most of the fires, and the deaths, were in the coastal region north of San Francisco that encompasses wine country. Four deaths came further inland in Yuba County.

While the Oakland Hills fire of 1991 killed 25 people by itself and the Griffith Park fire in Los Angeles in 1933 killed 29, never in recorded state history have so many people been killed by a simultaneous series of fires, said Daniel Berlant, a deputy director with the California Department of Forestry and Fire Protection.

Firefighters had reported modest gains against the blazes, but containment seemed nowhere in sight.

More than 8,000 firefighters were battling the blazes, and more manpower and equipment was pouring in from around the country and from as far away as Australia, officials said.

Since igniting Sunday in spots across eight counties, the fires have transformed many neighbourhoods into wastelands. At least 3,500 homes and businesses have been destroyed and an estimated 25,000 people forced to flee.

The wildfires continued to grow in size. A total count of 22 fires on Wednesday fell to 21 on Thursday because two large fires merged, said state Fire Chief Ken Pimlott.

Fire officials were investigating whether downed power lines or other utility failures could have sparked the fires.

Hundreds of evacuees fled to beaches far to the north of the fires, some sleeping on the sand on the first night of the blazes.

Since then, authorities have brought tents and sleeping bags and opened public buildings and restaurants to house people seeking refuge in the safety and clean air of the coastal community of Bodega Bay.